The escalating legal battle over the rights to the iPad name in China has reached a Shanghai courtroom, in a case that could prevent Apple selling the wildly popular tablet computer in the country's commercial heartland.

Lawyers for Proview, a Chinese television manufacturer which claims it owns the rights to the trademark in the country, made an impassioned plea for support from a judge yesterday, saying that Apple was costing it up to $2bn (£1.3bn) in profits.

They showed the court a thin computer, packed tightly in a cardboard box, that they said was their own "Ipad", or Internet Personal Access Device.

But at the fractious four-hour hearing, Apple's lawyers said the US tech giant bought the rights to the name from Proview in 2009, and that the trademark was probably invalid anyway.

"Proview has no product, no markets, no customers and no suppliers. It has nothing," said Hu Jinnan, Apple's attorney. "Apple has huge sales in China. Its fans line up to buy Apple products. The ban, if executed, would not only hurt Apple sales but it would also hurt China's national interest."

Proview, whose business has fallen into financial difficulties, is pursuing Apple in courts throughout China,and has even tried to get the government to ban imports of iPads.

Last week, it said it had won an injunction on one independent retailer of the device in the southern city of Huizhou, but a victory in Shanghai would be dramatic because three of the five Chinese Apple Stores are there.